Typically, telecommunication systems that provide broadband access to residential customers contain a residential gateway which consists of an xDSL (any type of digital subscriber line generally communicated over copper lines) modem or xPON (any type of passive optical network generally communicated over optic fibers) interface combined with various local area networking (LAN) technologies to enable sharing the broadband access with other computers or devices within the residence. Wireless local area network (WLAN) standards and home phone line networking (HPNA) are examples of such LAN technologies. In addition, some telecommunication systems may provide a voice-over-internet-protocol (VOIP) feature to allow telephone calls via the broadband link. Some systems may, in addition to broadband access sharing, need to distribute broadband media content such as video streams into various locations within the residence.
Typically, the residential gateway is located inside the house. In certain cases, however, it may be desirable to locate the residential gateway outside the house at a network interface device (NID), such as for example, the intelligent Network Interface Device (iNID) made by 2Wire, Inc., of San Jose, Calif. An NID is the point of demarcation between the Unbundled Network Element (UNE) loop and the end user's inside wire. In general, there is often no external source of alternating current (AC) power accessible at the NID or iNID location. Consequently, powering the device from an isolated direct current (DC) power source inside the house is the generally viable option. DC power transmission lines are used to provide power to the outside device.
A significant problem in trying to locate the residential gateway at the NID or iNID is the problem of sending communication signals between the power supply unit (PSU) and the outside device. Conventional schemes for sending communication signals involve the installation of separate wires between the outside device and the power supply unit for the purpose of facilitating communication. These schemes often require creating additional holes in the exterior and/or interior walls of buildings. Additional labor and material expense is associated with this additional separate wiring.
Other conventional schemes may try to solve the problem of requiring additional separate wiring by making use of carrier current communications. Carrier current communications systems operate by impressing a modulated carrier signal on the existing DC power transmission wires. In a carrier current communications system, a transmitter in the power supply unit typically modulates a carrier signal with the desired data and transmits the modulated carrier signal across the power transmission lines. A receiver in the outside device receives the carrier waves and demodulates the carrier signal to extract the data signal. The data signal may then be used by the residential gateway as needed. One drawback of conventional carrier current communications systems is that the receivers and transmitters generally have a complex proprietary design making them expensive to implement.